The present invention relates to a method of preparing humus, particularly stable humus, from organic waste material, and the humus product thereof. The invention also relates to an apparatus for performing this method.
An increasingly pressing problem in the area of waste disposal exists due to the rising costs of and limited space for landfills. Waste management companies and municipalities continue to search for viable alternatives. These include recycling, incineration and composting.
The common goal of waste treatment and recycling methods is to process waste safely and at a low cost, while using as much of the waste as possible to produce useful products. The more waste is transformed into usable products or energy, the less volume of the original waste remains to be disposed. Waste management alternatives to landfills seek to maximize waste conversion and minimize costs.
Recycling allows valuable raw materials such as paper, glass, aluminum and iron to be recovered from waste and reused. The benefits of recycling include a reduction of waste volume, conservation of raw materials, reduced toxicity within the environment and conservation of valuable land otherwise required for landfills. The major problem with respect to recycling is that recyclable waste must be separated before it can be processed. The public is not yet conditioned to methodically separate all recyclable waste from the non-recyclable waste.
The second alternative in consideration, is often seen as the easy alternative to landfills. The waste is simply burned and the bound energy recovered. Though effective in reducing waste volume, these methods are expensive in terms of high capital costs, the high costs of maintenance, the control of dangerous and/or toxic emissions, and disposal of the residual ash. The danger to the environment posed by incineration and the expense are often too great to be outweighed by the gains in energy and waste reduction.
The third alternative is composting. This natural process offers a reduction in the volume of organic waste while producing natural fertilizer in the form of humus. Since only organic material can be composted, separation of non-organic waste is required. Traditional composting techniques such as "windrowing", takes up to one year to transform all organic waste into humus. Several existing techniques attempt to increase the composting efficiency so that humus can be obtained in three to four months. Examples of these techniques are those that use tunnel-type reactors and screening systems as well as large digester systems.
Most of the techniques for increasing composting efficiency involve the use of apparatus that require a large area to complete the conversion of the organic waste material to humus. The separation involved and the time and space requirements to complete the composting are drawbacks that have limited the use of composting on a large industrial scale.
Other composting techniques have used reactors to maintain the microbial growth in the organic waste material. However, such reactor techniques have suffered from an inability to maintain an optimum growth environment throughout the mass of the organic waste material. This is due in part to the packing of the organic waste material which prevents sufficient reaction to allow efficient microbial respiration. Another disadvantage arises from the failure to control the temperature throughout the organic material. An example of a prior an reactor is disclosed in U.S. Pat. No. 3,930,799 to Eweson, which is hereby incorporated herein by reference.
It is therefore desirable to develop a high efficiency composting system which requires less time and curing area to produce a high quality humus product.
The present invention relates to a method and related apparatus for producing a consistently high quality humus product with greater throughput over time, which translates to greater efficiency. This results largely from reduced reactor retention time made possible by the present invention. The humus product of the present invention is stable and can be specially applied to enrich soil in household and/or industrial agriculture environments.